Cable splice closure

ABSTRACT

A cable splice closure ( 10 ) comprising a casing ( 12 ) which is capable of being closed around a cable splice, and at least one cable retention means ( 24 ) for retaining the end of at least one cable ( 22 ) fed into the interior ( 20 ) of the closure through or adjacent to a seal ( 44 ), the said retention means ( 24 ) being capable of being tightened, in use, to hold the seal ( 44 ) against the said cable ( 22 ) to seal the closure ( 10 ) and to retain the said cable ( 22 ) substantially independently of any force applied to the retention means ( 24 ) by the casing ( 12 ).

This invention relates to a cable splice closure, a kit of parts and acable retention unit therefor.

Many different types of cable splice closure are known. For example,International Patent Application No. PCT/GB96/00194 discloses atelecommunications cable splice closure comprising a pair ofsemi-cylindrical elongate casing parts which can be brought togetheraround a cable splice to close the closure with the cable splice locatedin the interior of the closure. The closure includes a pair of cableretention grippers which can be operated, that is to say tightenedagainst the surface of the cable, from the exterior of the casing parts.

The cable ends that feed into the interior of the closure are gripped bythe cable grippers at respective opposite longitudinal ends of thecasing by tightening the jaws of the grippers around the exteriorsurface of the cable. The grippers are slidably mounted in respectiveslots in the casing parts at the cable openings at the respectivelongitudinal ends of the casing.

To enclose a cable splice, strips of sealing material, which may bemastic or gel for example, are wrapped around the cables on oppositesides of the splice. Each gripper is located adjacent to a respectiveseal on the opposite side of the seal to the cable splice. The jaws ofthe cable gripper are tightened around the cable by tightening one ormore screw-threaded bolts or other fastening means extending out of thecasing. The cable grippers are located in the respective slots and thecasing parts are brought together along their opposing longitudinaledges and secured together by threaded fasteners along the longitudinaledges of the casing parts. This arrangement allows the closure to beclosed around a cable splice before it is tightly secured to the cables,thus permitting adjustments to the position of the closure with respectto the cables after it has been closed around the splice, that is to saythe position of the cable splice can be adjusted within the closedenclosure before the cables that are fed into the closure are secured bytightening the jaws of the cable grippers around the exterior surface ofthe respective cables.

The closure described in PCT/GB/96/00194 is quite complex inconstruction, containing a large number of parts which have to beassembled together by the installation engineer in order to secure thesplice cables to the closure and ensure that the closure is correctlysealed. Consequently, installation of a cable splice closure around acable splice is often time-consuming and normally requires a high degreeof skill and training on the part of the installation engineer. Forexample, the installation engineer must ensure that the grippingpressure of the jaws of the cable grippers is sufficient to preventaxial pullout of the cables from the closure but insufficient to damagethe insulation or outer cladding of the cable. Similar considerationsapply to the tightening of the fasteners along the longitudinal edges ofthe casing parts.

There is a requirement therefore to provide an improved cable spliceclosure which is easy to install around a cable splice, which is simplein construction, and which has only a small number of components whileensuring it is inexpensive to manufacture, that provides goodenvironmental sealing, and that substantially prevents forces,particularly axial and bending forces, which may act on the cables, fromdamaging a splice enclosed by the closure. There is a furtherrequirement to provide an improved cable splice enclosure which can beinstalled by hand by the installation engineer without usinginstallation tools etc., while ensuring a pre-determined load is appliedto the cables fed into the enclosure to hold the cables with respect tothe closure.

According to an aspect of the present invention, there is provided acable splice closure comprising a casing which is capable of beingclosed around a cable splice, and at least one cable retention means forretaining the end of at least one cable fed into the interior of theclosure through or adjacent to a seal, the said retention means beingcapable of being tightened, in use, to seal against and retain the saidcable substantially independently of any compressive force applied tothe retention means by closure of the casing.

In the present invention the cable or cables fed into the interior ofthe closure are retained by the cable retention means to resist axialforces acting to pull the cables out of the closure; torsion; andbending. Compression of the retention means around the cable(s) isachieved substantially independently of the casing parts, that is to saythe seal against the cable or cables is not directly compressed by theaction of the casing parts being brought together to close the closure.The cable retention means is retained by engagement formations of thecasing parts to hold the cable or cables with respect to the closure.This readily enables the cable retention means to be used for differentsize closures, that is to say for a range of casing sizes havingengagement formations of similar size. The present invention thereforecontemplates a modular type system for cable splice closures in whichidentical or substantially identical cable retention means are used withdifferent size casing parts.

Preferably, the retention means is capable of being opened so that itmay be placed substantially around the cable or the seal and the cableand closed to hold the seal against the cable. Preferably, the cableretention means is provided with a snap fit type closure means so thatthe retention means is capable of being opened and closed around thecable independently of the use of installation tools by the installationengineer.

Preferably, the retention means applies a pre-determined load to theseal and cable when closed. This readily enables uniform and completeclosure of the cable retention means to be achieved. This may beimplemented by the aforementioned snap fit closure means of the cableretention means which enables closure of the retention means around thecable to seal in a single operation by the installation engineer withoutusing installation tools. This can reduce the craft sensitivity of theinstallation and improve the reliability of the installation and reducethe installation time.

In other embodiments the cable retention means may be closed by otherfastening means such as screws or bolts or the like but these are lessdesirable since the quality of the installation may vary as theinstallation engineer may fail to fully tighten the fasteners to holdthe cable retention means around the cable and seal.

In preferred embodiments, the seal is resilient so that it may bedeformed to seal around the cable or cables when the cable retentionmeans is closed. In this way compression of the seal not only acts tohold the cable with respect to the cable retention means by frictionalcontact with the cable but also provides an effective environmental sealbetween the cable retention means and the cable or cables being held bythat retention means. This is particularly advantageous as cables havingdifferent diameters may be fed through the seal and retention means intothe interior of the closure. Compression of the seal, to a lesser orgreater extent depending upon the diameter of the cable, readily enablesdifferent size (diameter) cables to be held by compression of the seal.This is important where the cables being fed into the closure arecapable of being changed, for example to reconfigure the wiring oroptical fibre connections in a telecommunications network.

In preferred embodiments, the seal comprises at least one aperture orslot for receiving a length of cable being fed into the enclosure. Theslot may be a radial slot so that the cable can be readily inserted inthe slot from the outer periphery of the seal. Alternatively oradditionally cable may be fed into the enclosure through an aperture inthe seal either by threading the cable through the aperture or morepreferably by providing a slit in the seal so that the seal may beopened between the aperture and the periphery of the seal for receivingthe cable. Where slots or apertures are used cable blanks may beinserted into empty slots or apertures to maintain the the seal, whennot all the slots/apertures are required for cables at a particular timein a particular installation.

In preferred embodiments the seal comprises an elastomeric material,preferably the seal is formed of a thermoplastic elastomer, preferablywith a layer of gel or gel-type material sandwiched between outer layersof thermoplastic elastomer.

In preferred embodiments the cable retention means substantiallysurrounds the seal and cable when in the closed position. Preferably,the cable retention means comprises at least two clamping members whichare capable of being brought together to hold the seal against thecable. More preferably the cable retention means comprises a pair ofclamping members which are pivotally movable with respect to oneanother. Preferably, the pair of clamping members are hinged together sothat the cable retention means constitutes a single modular component ofthe cable splice closure of the present invention.

Preferably, the clamping members are generally arcuate so that they arecapable of surrounding the cable and seal when they are broughttogether. In preferred embodiments the clamping members comprise a pairof semi-circular type half shells which, when they are brought together,provide an aperture in the form of a central bore in which the seal islocated and through which the cable or cables are fed into the interiorof the closure.

Preferably, the clamping members are held together by fastening means.The fastening means may be hand operated. A preferred fastening meanscomprises a latch and a preferred latch comprises an over the centretype latch. The term “over the centre” refers to the type of latch wherethe latch is biased away from a centre position in both directions suchthat an increasing closing force is first required to move the latch toits centre position where the force acting on the latch is a maximum andthen reduces as it is moved from the centre to its closed position.

Preferably, the retention means is retained in the interior of theclosure by engagement with the casing parts. The casing parts may beprovided with integral engagement features for engagement with the cableretention means, for example slots or cavities or the like for receivingthe cable retention means. Such engagement features may be incorporatedin the casing parts during manufacture, for example integrally mouldedwith the casing parts in embodiments where the casing parts are moulded.The retention means may be sealed therein by known sealing materials toenhance sealing of the closure as a whole.

In preferred embodiments, the casing parts comprise a pair of halfshells which are capable of being brought together along respectiveopposing edges thereof to close the closure. This readily enables thecable splice to be positioned in one of the two half shells before theother half shell is fitted to close the closure. In preferredembodiments the half shells are hinged together so that the shells canbe readily closed.

In preferred embodiments, the casing parts are provided with latch meansfor holding the parts together and thereby retaining the cable retentionmeans in the interior of the closure. Preferably the latch meanscomprises an over the centre type latch so that the casing parts may bereadily brought together and closed in a simple and effective mannerwithout the use of installation tools.

In preferred embodiments the casing parts comprise at least one open endfor feeding the cable into the interior of the closure, and at least oneof the cable retention means is positioned at the or each open end forclosing the end of the closure. In this way the cable retention meansalso provides an end closure for the cable splice closure casing parts.In embodiments where two or more cable retention means are provided atone end of a cable splice closure a further environmental seal may beprovided between the cable retention means by introducing a gel ormastic type sealant in the region between the two cable retention means.In this way moisture or other contaminants can be prevented fromentering the region of the closure containing the cable splice from theopen end or ends of the casing parts.

According to another aspect of the invention there is provided a kit ofparts for enclosing a cable splice comprising:

-   -   a casing which is capable of being closed to close the closure;    -   at least one compressible seal; and,    -   at least one cable retention means for retaining the end of at        least one cable fed into the interior of the closure through or        adjacent to a compressible seal, the said retention means being        capable of being tightened, in use, to compress the seal around        the said cable to retain the said cable substantially        independently of any force applied to the retention means by the        casing.

According to another aspect of the invention there is provided a cableretention unit for a cable splice enclosure of the type having at leasttwo casing parts which are capable of being brought together to closethe closure, the retention means being capable of being opened so thatit may be placed substantially around a cable or cables to be retained,and comprising closure means for applying a pre-determined clamping loadto the cables when the retention unit is closed.

Various embodiments of the present invention will now be moreparticularly described, by way of example only, with reference to theaccompanying drawings, in which:

FIG. 1 shows an open cable splice closure according to an embodiment ofthe present invention;

FIG. 2 is a perspective view of a cable retention unit for the closureof FIG. 1, with the cable retention means in an open configuration;

FIG. 3 is a perspective view of the cable retention means of FIG. 2 in aclosed configuration;

FIGS. 4 and 5 are cross-section views of the cable retention unit ofFIGS. 2 and 3 shown in open and closed configurations; and

FIGS. 6 and 7 are cross-section views of another cable retention unitsimilar to that shown in FIGS. 2 and 3.

Referring to FIG. 1, a cable splice closure 10 according to anembodiment of the present invention comprises a pair of half shell halfcylinder casing parts 12 which are capable of being brought togetheralong their respective longitudinal edges 14 to close the closure. Thecasing parts each define one half of a hollow cylindrical casing whichis provided on its exterior surface with a plurality of fastening means16 spaced apart along the length of the casing for fastening the twoparts together. The fastening means 16 in this particular embodiment arehand operable over the centre type latches which apply a pre-determinedclamping force to the casing parts to hold the casing parts together. Asshown in FIG. 1 three such latches 16 are provided on one side of thecasing only with the casing parts being hinged together along theiredges on the other side of the casing. Sealing strips 18 which maycomprise elastomeric material are provided along the adjoininglongitudinal edges of the casing parts to seal the interior 20 of theclosure when the casing parts are brought together.

Cable ends 22 extend into the interior of the closure and form part of acable splice. In the illustration of FIG. 1 only the cable ends areshown for the purpose of illustrating the present invention. It will bereadily understood, however, by those skilled in the art, that the cableends are joined together by known connectors to form in a cable splicepositioned within the interior of the closure between the ends of thecables shown.

The cable ends 22 pass into the interior of the closure and are retainedwith respect to the closure by four cable retention units 24 which arepositioned in pairs near the respective axial ends of the casing parts.The cable retention units 24 of each pair are spaced apart at eachrespective end of the closure by an amount substantially equal to theaxial dimension of each retention unit. The region 25 between theretention units 24 at each end of the closure is provided for receivingsealing material such as gel or other suitable material for providing anenvironmental seal at the respective ends of the closure.

The cables are held by the cable retention units so that they resistaxial pullout forces acting on the cables and also bending and torsionof the cables. The cable retention units hold the ends of the respectivecables substantially independently of any force that is applied to theretention units by closure of the casing parts. Thus, no load, orsubstantially load, is transferred in the assembled closure between thecasing parts and the cables fed into the closure.

As can be seen in FIG. 1, the cable retention units are located in theinterior of the closure by engagement with radial protrusions 26 on theinterior surface of the casing parts. The protrusions 26 engage theaxial side surfaces 27 of the retention units to prevent axial movementof the retention units within the interior of the closure.

The manner in which the cables are retained by the cable retention unitswill now be described. Referring to FIG. 2, each cable retention unit 24comprises a pair of semi-circular shaped clamping members 28 and 30which are hinged together on one side thereof by a pin 32 so that theymay be opened and closed, that is to say moved away from each andbrought together. The semi-circular clamping members 28 and 30 provide asubstantially circular cross-section central bore through which thecable ends 22 are fed into the enclosure. On the opposite side of thecable retention unit to the hinge 32 the clamping members are providedwith an over the centre type latch 34 which comprises a stainless steelU-shaped clip or ring 36 and a lever member 38. The clip 36 is pivotallyconnected to the proximal end of the lever and extends circumferentiallyso that it may engage a suitable protrusion 39 on an engaging part ofthe clamping member 28. The lever 38 is provided with a cam surface 40(as shown in FIGS. 4 and 5) which cooperates with a similarly shaped camsurface 42 on the exterior of clamping member 30 to bring the clampingmembers together when the lever is pivoted towards the clamping member30.

The cable retention unit 24 is thus capable of being opened to be placedaround cables 22 fed into the interior of the closure and closed bymeans of the over the centre latch 34 to retain the cables with respectto the retention unit. Retention of the cables is achieved bycompression of a sealing element 44 positioned around the cables in theinterior bore of the cable retention unit. As can best be seen in thedrawing of FIG. 3, the sealing element 44 comprises a series of radialslots for receiving respective cable ends such that the cables aresubstantially surrounded by the compressible sealing element prior toclosure of the retention unit 24. The sealing element preferablycomprises a gel type material surrounded by a thermoplastic elastomerouter layer.

Closure of the cable retention unit 24 using the over centre latch 34causes the clamping members 28 and 30 to be brought together compressingthe sealing element 44 around the outer periphery of the cables until apre-determined clamping load is applied to the cables through thecompressed sealing element when the clamping members are broughttogether to the fully closed position as shown in FIG. 3. In thisposition movement of the cables with respect to the retention unit isresisted by the compression forces acting in the sealing element againstthe cables. In the closed position shown in FIG. 3 the sealing elementtherefore not only acts to retain the cables but also provides anenvironmental seal to prevent or substantially prevent ingress ofmoisture and/or other contaminants into the interior of the enclosure.It is to be understood that the lever 38 and loop type clip 36 aredetachable from the clamping members since the clip 36 is arranged tohook over the protrusion 39 (or other engagement means) to attach itselfand the lever to the clamping member 28.

FIGS. 6 and 7 show a slightly modified cable retention unit 24 where theover centre latch is incorporated in the clamping members 28 and 30. Inthis arrangement the cam surface 42 is provided on the clamping member28 and the lever 38 is replaced by the clamping member 30 with the camsurface 40 provided on the clamping member 30. In this arrangement thetwo clamping members are not hinged together but are pivotally connectedtogether by means of a pressing lever 48. The lever 48 joins oppositesides of the clamping members 28 and 30 together. The cable retentionunit of FIGS. 6 and 7 is closed by engagement of the respective camsurfaces 40 and 42 and rotation of the clamping member 30 about theengaging cam surfaces towards the clamping member 28. Rotation of theclamping member 30, which now acts as a lever, brings the clampingmembers 28 and 30 together and tensions the hook 36 so that the clampingmembers are held together in the closed position shown in FIG. 7.

In the embodiments described with reference to FIGS. 2-7 the cableretention unit 24 is provided with an over the centre type latch 34 sothat the retention units may be applied to the cables in a simpleinstallation operation without the use of installation tools. However,in the arrangement shown in FIG. 1 the clamping members 28 and 30 aresecured together by means of fastening screws 50 such that tightening ofthe screws causes the sealing element 46 to be compressed around thecables being fed into the enclosure.

Preferably the cable retention units described herein are mouldedpolycarbonate or polyacetal material.

Although aspects of this invention have been described with reference tothe embodiments shown in the accompanying drawings, it is to beunderstood that the invention is not limited to those preciseembodiments and that various changes and modifications may be effectedwithout further inventive skill and effort. For example, the closurecasing may be a one-piece integral structure such as a flexible andresilient tubular element that is split along its length so that it maybe opened to receive one or more cable retention units 24. The one-piececasing may be of a resilient elastomeric material such as rubber.

1. A cable splice closure comprising a casing which is capable of beingclosed around a cable splice, and at least one cable retention means forretaining the end of at least one cable fed into the interior of theclosure through or adjacent to a seal, the said retention means beingcapable of being tightened, in use, to seal against and retain the saidcable substantially independently of any compressive force applied tothe retention means by the casing.
 2. A cable splice closure as claimedin claim 1 wherein the retention means is capable of being opened sothat it may be placed substantially around the cable or the seal and thecable and closed to hold the seal against the cable.
 3. A cable spliceclosure as claimed in claim 2 wherein the said retention means applies apredetermined load to the seal and cable when closed.
 4. A cable spliceclosure as claimed in claim 1 wherein the seal is resilient.
 5. A cablesplice closure as claimed in claim 1 wherein the seal comprises at leastone aperture or slot for receiving a length of cable being fed into theclosure.
 6. A cable splice closure as claimed in claim 1 wherein theseal comprises an elastomeric material.
 7. A cable splice closure asclaimed in claim 6 wherein the seal comprises a layer of gel typematerial and an outer layer of elastomeric material.
 8. A cable spliceclosure as claimed in claim 6 wherein the elastomeric material comprisesa thermoplastic elastomer.
 9. A cable splice closure as claimed in claim1 wherein the retention means substantially surrounds the seal andcable.
 10. A cable splice closure as claimed in claim 1 wherein theretention means comprises at least two clamping members which arecapable of being brought together to hold the seal against the saidcable.
 11. A cable splice closure as claimed in claim 10 wherein thesaid retention means comprises a pair of clamping members which arepivotally movable with respect to each other.
 12. A cable splice closureas claimed in claim 11 wherein the said clamping members are hingedtogether.
 13. A cable splice closure as claimed in claim 11 wherein thesaid clamping members are generally arcuate so that they are capable ofsurrounding the said cable and seal when brought together.
 14. A cablesplice closure as claimed in claim 11 wherein the clamping members areconnected together to provide a clamping ring around the said cable whenbrought together.
 15. A cable splice closure as claimed in claim 10wherein the said clamping members are held together by fastening means.16. A cable splice closure as claimed in claim 15 wherein the saidfastening means is/are hand operable.
 17. A cable splice closure asclaimed in claim 15 wherein the said fastening means comprises a latch.18. A cable splice closure as claimed in claim 17 wherein the said latchcomprises an over the centre type latch.
 19. A cable splice closure asclaimed in claim 1 wherein the said retention means is retained in theinterior of the closure by engagement with the said casing.
 20. A cablesplice closure as claimed in claim 1 wherein the casing parts comprise apair of half shells which are capable of being brought together alongrespective opposing edges thereof to close the closure.
 21. A cablesplice closure as claimed in claim 1 wherein the said casing is providedwith fastening means for holding the casing in a closed configurationthereby retaining the said retention means in the interior of theclosure.
 22. A cable splice closure as claimed in claim 1 comprising aplurality of said cable retention means.
 23. A cable splice closure asclaimed in claim 1 wherein the casing comprises at least one open endfor feeding the said cable into the interior of the closure, and atleast one of the said cable retention means is positioned at the or eachopen end for closing that end of the closure.
 24. A cable splice closureas claimed in claim 23 wherein a pair of cable retention means areprovided, in spaced relation, at the or each open end of the closure.25. A cable splice closure as claimed in claim 1 wherein the casingcomprises at least two casing parts which are capable of being broughttogether to close the closure.
 26. A kit of parts for enclosing a cablesplice comprising a casing which is capable of being closed to close theclosure; at least one compressible seal; and, at least one cableretention means for retaining the end of at least one cable fed into theinterior of the closure through or adjacent to a compressible seal, thesaid retention means being capable of being tightened, in use, tocompress the seal around the said cable to retain the said cablesubstantially independently of any force applied to the retention meansby the casing parts.
 27. A cable retention unit for a cable spliceclosure of the type having at least two casing parts which are capableof being closed around a cable splice, the retention unit being capableof being opened so that it may be placed substantially around a cable orcables to be retained, and comprising closure means for applying apre-determined clamping load to the cables when the retention unit isclosed.
 28. A cable retention unit as claimed in claim 27 wherein theclosure means comprises at least one over the centre latch means.